feat(historian-gateway): alarm-write cutover — AddAlarmHistorian drains to GatewayAlarmHistorianWriter

Claude-Session: https://claude.ai/code/session_012SDSQ3AcaXqPcBtDESBRii

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Gateway/GatewayHistorianServiceCollectionExtensions.cs

@@ -2,16 +2,17 @@ using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Logging.Abstractions;
 using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+using ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian;
 using ZB.MOM.WW.OtOpcUa.Runtime.Historian;
 
 namespace ZB.MOM.WW.OtOpcUa.Driver.Historian.Gateway;
 
 /// <summary>
-///     Host-callable factory that builds the gateway-backed server-side HistoryRead data source. The
-///     Host's <c>AddServerHistorian</c> wiring supplies <see cref="CreateDataSource"/> as its
-///     <c>Func&lt;ServerHistorianOptions, IServiceProvider, IHistorianDataSource&gt;</c>, keeping the
-///     concrete package-client dependency inside this driver project (the Host references only the
-///     driver, not the package client directly).
+///     Host-callable factories that build the gateway-backed historian seams against the single
+///     <c>ServerHistorian</c> gateway: <see cref="CreateDataSource"/> for the read path (the Host's
+///     <c>AddServerHistorian</c> wiring) and <see cref="CreateAlarmWriter"/> for the alarm-write path
+///     (the Host's <c>AddAlarmHistorian</c> wiring). Both keep the concrete package-client dependency
+///     inside this driver project — the Host references only the driver, not the package client directly.
 /// </summary>
 public static class GatewayHistorian
 {
@@ -39,4 +40,42 @@ public static class GatewayHistorian
             HistorianGatewayClientAdapter.Create(options, loggerFactory),
             logger);
     }
+
+    /// <summary>
+    ///     Builds a <see cref="GatewayAlarmHistorianWriter"/> over a lazily connected
+    ///     <see cref="HistorianGatewayClientAdapter"/> mapped from the bound
+    ///     <see cref="ServerHistorianOptions"/> — the <b>same single gateway</b> the read path
+    ///     (<see cref="CreateDataSource"/>) targets. The Host's <c>AddAlarmHistorian</c> wiring supplies
+    ///     this as the concrete <see cref="IAlarmHistorianWriter"/> the durable
+    ///     <c>SqliteStoreAndForwardSink</c> drain worker delegates to, sourcing the connection from the
+    ///     <c>ServerHistorian</c> section (endpoint/key/TLS) rather than the legacy Wonderware-shaped
+    ///     <c>AlarmHistorian</c> host/port. Resolves an <see cref="ILoggerFactory"/> and the writer's
+    ///     <see cref="ILogger{TCategoryName}"/> from <paramref name="services"/>, falling back to the null
+    ///     implementations when absent. Performs no network I/O — the underlying channel dials on first send.
+    /// </summary>
+    /// <remarks>
+    ///     This deliberately constructs its <b>own</b> <see cref="HistorianGatewayClientAdapter"/> — a
+    ///     second gRPC channel to the same gateway as the read path. Collapsing the two onto one shared
+    ///     channel would require the container to own a singleton <see cref="IHistorianGatewayClient"/> and
+    ///     the read-side <see cref="GatewayHistorianDataSource"/> to stop owning + disposing its client,
+    ///     regressing the read cutover's dispose ownership (and its tests). A second channel to a co-located
+    ///     sidecar is cheap — the gateway pools and amortizes the underlying historian sessions server-side —
+    ///     so each path keeps its own channel with a clean, independent lifetime.
+    /// </remarks>
+    /// <param name="options">The bound <c>ServerHistorian</c> configuration (endpoint, key, TLS posture).</param>
+    /// <param name="services">The resolving service provider (used only to locate logging services).</param>
+    /// <returns>The gateway-backed <see cref="IAlarmHistorianWriter"/>.</returns>
+    public static IAlarmHistorianWriter CreateAlarmWriter(ServerHistorianOptions options, IServiceProvider services)
+    {
+        ArgumentNullException.ThrowIfNull(options);
+        ArgumentNullException.ThrowIfNull(services);
+
+        var loggerFactory = services.GetService<ILoggerFactory>() ?? NullLoggerFactory.Instance;
+        var logger = services.GetService<ILogger<GatewayAlarmHistorianWriter>>()
+            ?? NullLogger<GatewayAlarmHistorianWriter>.Instance;
+
+        return new GatewayAlarmHistorianWriter(
+            HistorianGatewayClientAdapter.Create(options, loggerFactory),
+            logger);
+    }
 }